Restarting a Remote Network

Issues related to configuring your network
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easyprosys
Posts: 16
Joined: 2012/03/25 09:36:51

Restarting a Remote Network

Post by easyprosys » 2015/03/31 08:44:56

After issuing a ethtool -s eth0 speed 10 I still see the port speed is 1000Mb/s. Do I need to restart the network after making the change? My data center is 2 hrs. away and, well, as a rookie it scares me. If it hangs... It sucks being green. :roll: I've Googled it and cannot find the answer.

I appreciate you guys.

aks
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Joined: 2014/09/20 11:22:14

Re: Restarting a Remote Network

Post by aks » 2015/03/31 19:21:35

So what's the question? Do you mean if you set the interface to a specific speed (assuming ethernet here) will it disconnect? Well the answer lies somewhere between in what way your particular interface will react and what the switch port (i.e.: the physical port (or even the virtual port)) you are connect to will react.
For example some switches allow a port to only connect at (say) 10/full, 100/full and all else would be rejected. If that's the case and you configure the interface at (say) 10/Half, link would not be correctly established and the host would experience a lot of "network errors".

easyprosys
Posts: 16
Joined: 2012/03/25 09:36:51

Re: Restarting a Remote Network

Post by easyprosys » 2015/04/04 12:14:35

Thank you for your reply. The question does seem unclear. I am asking if I need to restart the network after changing the port speed.

My servers are SuperMicros with Asus server boards. The command seems so straight forward and therefore my questioning.

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TrevorH
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Re: Restarting a Remote Network

Post by TrevorH » 2015/04/04 12:37:46

No, I'm pretty sure that if you restart the network service then it will revert any changes you made using ethtool.

What is your actual goal here? If you need to restrict your connection to 10Mbps like that then you probably have a hardware error - faulty cable or network switch port, that sort of thing. If you want to limit the bandwidth available then that's probably not the way to do it, perhaps you need to look at the tc command instead.
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easyprosys
Posts: 16
Joined: 2012/03/25 09:36:51

Re: Restarting a Remote Network

Post by easyprosys » 2015/04/28 22:20:13

Thanks very much for your reply. I sure appreciate it. I have a small hosting operation for marketing customers. We are getting pounded by bots that spike our 100Mb/s connection across a bunch of servers. Even with our KVM/IP I cannot gain remote access because there isn't anymore bandwidth. I naively thought that if I rate restricted the interface it couldn't spike beyond 10Mb/s. But the port speed never changes. If there is a better solution I'd be happy to learn something new.

Code: Select all

{jim@hw003 ~}# ethtool eth0
Settings for eth0:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 1000baseT/Full 
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Half 1000baseT/Full 
        Advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: g
        Wake-on: g
        Current message level: 0x000000ff (255)
        Link detected: yes
Thank you for your helpful advice.

easyprosys
Posts: 16
Joined: 2012/03/25 09:36:51

Re: Restarting a Remote Network

Post by easyprosys » 2015/04/28 22:27:49

AWESOME! Thanks for the hint, Trevor!!! I did not know of the TC command. I just need to learn the syntax to limit eth0 to 5Mb/s. We do use Virtuozzo but I assume that if I rate limit the nic it would be global? Now to learn the command.

easyprosys
Posts: 16
Joined: 2012/03/25 09:36:51

Re: Restarting a Remote Network

Post by easyprosys » 2015/04/28 22:50:40

Oh my gosh. I hate to asak, I know that you're busy and like folks to learn on their own. But coiuld you help me undestand this? This is how to rate limit the NIC and the virtual port.

Code: Select all

Limiting outgoing bandwidth

We can limit container outgoing bandwidth by setting the tc filter on eth0.

DEV=eth0
tc qdisc del dev $DEV root
tc qdisc add dev $DEV root handle 1: cbq avpkt 1000 bandwidth 100mbit
tc class add dev $DEV parent 1: classid 1:1 cbq rate 256kbit allot 1500 prio 5 bounded isolated
tc filter add dev $DEV parent 1: protocol ip prio 16 u32 match ip src X.X.X.X flowid 1:1
tc qdisc add dev $DEV parent 1:1 sfq perturb 10

X.X.X.X is an IP address of container.
Limiting incoming bandwidth

This can be done by setting the tc filter on venet0:

DEV=venet0
tc qdisc del dev $DEV root
tc qdisc add dev $DEV root handle 1: cbq avpkt 1000 bandwidth 100mbit
tc class add dev $DEV parent 1: classid 1:1 cbq rate 256kbit allot 1500 prio 5 bounded isolated
tc filter add dev $DEV parent 1: protocol ip prio 16 u32 match ip dst X.X.X.X flowid 1:1
tc qdisc add dev $DEV parent 1:1 sfq perturb 10

Note that X.X.X.X is an IP address of container. 
I really like to learn this. I want to rate limit at 5Mb/s. Would this be a start-up script in rc.local?

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